As a Lewis acid catalyst used in cationic polymerization, AlCl3 catalyst is one of the important catalysts widely used chemical industry, petroleum refining and pharmaceutical industry. Due to good catalytic effect, such catalysts have features such as high polymer yield, narrow molecular weight distribution and good selectivity in the catalysis of α-olefin oligomerization. Although it has very high activity, AlCl3 catalyst has obvious disadvantages as follows: (1) AlCl3 catalyst has strong causticity, which may easily cause damage to equipments such as reaction kettles and thus reduce service life of the equipment, leading to less usage; (2) a large quantity of wastewater is produced during the polymerization in the presence of AlCl3 catalyst, thus severe environmental pollution will be caused if the wastewater cannot be disposed in time; and (3) AlCl3 catalyst after reaction cannot be easily recovered such that numerous corrosive waste is produced, thus a post-treatment process becomes necessary.
JP 08505888B discloses a method for producing lubricant base oil through cationic polymerization, wherein decene polymer is produced in the presence of Lewis acid such as AlCl3, BF3 as the catalyst. Since a homogeneous system is used in the method, resulting in a high amount of halide such as AlCl3, BF3 in product, products having a low level of halide cannot be produced. What is more, BF3 is both expensive and easy to cause a series of environmental problems due to the corrosivity of fluorine. Since such catalysts are difficult to be separated and are hardly recycled while a number of troublesome industrial waste liquid is produced, the cost of production is increased. Meanwhile, the α-olefin polymer thus obtained has a low molecular weight, and the obtained lubricant thus has a low viscosity, which cannot meet the environmental requirement when used as a lubricant.
Therefore, in order to satisfy the requirement of green chemistry, solid acid catalysts such as supported metal oxide are developed to replace traditional catalysts such as AlCl3 and BF3, meanwhile immobilized AlCl3 catalysts are also studied widely. It is desirable to eliminate the current problems as above and convert the AlCl3 catalyst into an environmentally friendly catalyst, providing that the excellent characteristics of AlCl3 can be maintained. A supported AlCl3 catalyst is a novel, efficient and environmentally friendly solid acid catalyst. In recent years, it has attracted more attention due to its higher catalytic activities and mild reaction conditions, and is widely used in the research on polymerization and alkylation.
U.S. Pat. No. 2,927,087 firstly proposes a method for producing a supported AlCl3 catalyst by the reaction of AlCl3 vapor with infusible oxides such as alumina and silica having a hydroxyl group on the surface thereof. Moreover, it emphasizes the necessity to remove unreacted AlCl3 by purging carrier gas above 300° C. after the reaction.
U.S. Pat. No. 4,929,800 discloses that a catalyst with high activity in the isomerization or pyrolysis of alkanes can be produced by a process of dissolving aluminum trichloride in a solvent such as CCl4, CH3Cl or CH2Cl2, adding a carrier such as silica or alumina thereto, and refluxing the resultant at 50-80° C. under N2 protection and dark condition refluxing for several hours to days.
U.S. Pat. No. 6,002,060 indicates that alpha-olefin can be oligomerized or copolymerized in the presence of supported aluminum trichloride as a catalyst and an organic aluminum compound as an aid.
CN 1156338 and CN 1939590 disclose that immobilized AlCl3 catalysts are prepared by the gas-phase immobilization as follows: reacting fresh aluminum trichloride carried by N2 gas brought into a reaction tube having alumina with a double-pore structure of mesopore and macropore and a particles size of 20-200 mesh therein, wherein the chlorine content is 6.0-9.0 wt %. The catalysts have shown good catalytic activity and selectivity in isobutene polymerization of low degree, and exhibit good stability. However, noticeable pressure drop is observed in the reaction of a fixed bed reactor filled with catalysts in form of fine particles.